496 SMITHSONIAN MISCELLANEOUS COLLECTIONS [vor. 48 
fjords and sounds several miles wide, but it is not credible that it 
could have crossed the 40 miles of the Norwegian channel, if the 
latter had been formed and was always free of ice during the period in 
question. 1 have shown elsewhere, however, that this channel, if 
existing at the time, probably was frozen over in winter. But the 
smaller mammals cannot well be assumed to have wandered such 
a distance across the ice, and we are therefore compelled to conclude 
that the land connection was complete and uninterrupted at the 
time of this invasion. 
We have thus come to the result that a composite biota, con- 
sisting of numerous cryptogamous and phanerogamous plants with 
a full complement of terrestrial animals during some period of 
glacial times subsequent to the megaglacial climax invaded western 
Norway between 59° and 63° north latitude from Scotland over a 
continuous land bridge which did not stay uninterrupted long enough 
to allow the slow traveling species, among them the batrachians and 
fresh-water fishes, to pass over. 
VIIl.. “Tae SuBatTcANnaic (Bros 
Before concluding the biogeographical considerations involved it 
is desirable to refer briefly to the plants and animals more or less 
characteristic of the southern coast of Norway between Stavanger 
and Arendal, which following Blytt’s example have been termed 
the Subatlantic biota. Atthe western extremity of their distribution 
in Norway they meet the southern members of the Atlantic biota, 
their boundaries frequently overlapping. With a few of the more 
widely distributed species it is therefore sometjmes difficult to de- 
cide to which of the two groups they properly belong. One of these 
is the holly (Jlex aquifolium), for which reason I have entirely 
discarded the term “ Ilex-flora”’ as being ambiguous and confusing. 
A characteristic feature of the distribution of these Subatlantic 
plants is that they occur in Denmark, separated from Norway by 
the 60 miles (111 km.) wide arm of the North Sea known as 
Skagerak. In Britain and in Ireland some are wanting and the 
distribution of others is decidedly southern. 
We have seen above that Blytt and others regarded them as 
having invaded southern Norway from the south (p. 460) while other 
botanists maintain that they slowly crept along the west coast of 
Sweden into Norway. Many distributional facts, especially the 
lack of many of the species, living or fossil, in the intervening coun- 
try, militate against the latter theory, and after Sernander has 
